Cross-string telephone employing pushbuttons

ABSTRACT

A pushbutton is provided for use with cross-string conductors supported on a base plate. The elements of the pushbutton are made so that they may be assembled and attached to the board without the use of separate fasteners. Contact is completed between cross-string conductors on the base plate when a part of the push button, i.e., a V-shaped spring, touches them. The pushbutton incorporates a spring which biases it to a neutral position when it is not pressed against the conductors.

United States Patent Inventors Josef l-loier;

(iuenter Haage, Wien, Austria Appl, No. 724,574 Filed Apr. 26, 1968Patented Feb. 2, 1971 Assignee International Standard ElectricCorporation New York, N.Y. a corporation of Delaware Priority Apr. 28,1967 Austria 4065/67 CROSS-STRING TELEPHONE EMPLOYING PUSHBUTTONS 7Claims, 1 Drawing Fig.

U.S. Cl 200/166, 179/158 Int. Cl H0lh 3/12 Field of Search 200/ 1 75,

[56] References Cited UNITED STATES PATENTS 2,587,458 2/1952 Fritts200/l66( 1) 2,747,144 5/1956 Beers ...200/166(. 1 )(X) 3,051,799 8/1962Paul et a1. ..200/166(.1)(X) 3,060,784 10/1962 Holt i ..200/166(.1)(X)3,330,916 7/1967 Bauer ...200/l66(.1)(X) 3,392,250 7/1968 Ziegler et a1..200/166(. 1 )(X) Primary Examiner-H. 0. Jones AttorneysC. CornellRemsen, Jr., Rayson P. Morris, Walter J. Baum, Percy P. Lantzy, 1.Warren Whitesel and Delbert P. Warner ABSTRACT: A pushbutton is providedfor use with crossstring conductors supported on a base plate. Theelements of the pushbutton are made so that they may be assembled andattached to the board without the use of separate fasteners. Contact iscompleted between cross-string conductors on the base plate when a partof the push button, i.e., a V-shaped spring, touches them. Thepushbutton incorporates a spring which biases it to a neutral positionwhen it is not pressed against the conductors.

PATENTEU FEB 215m I nuenlors Illa/"ER 6. #19065 YdQ W A tlorneyCROSS-STRING TELEPHONE EMPLOYING PUSHBUTTONS The invention relates to aresilient electrical contacting device, such as is used in signallinginstallations, domestic bell systems and domestic telephone systems.

The resilient electric contacting device according to the inventionconsists of a movable contact carrier and a stationary contact carrier,which comprises at least two conductors; and is characterized in thatthe movable contact carrier comprises a flat base of plastics material,which has on one end a detachable key cap and on the other end aV-shaped wire spring, which is round or angular in cross section and hasa tip adapted to snap into an aperture of the flat base whereas its limbis guided by ribs of the base, the base is provided at the other endwith noses, which extend beyond the width of the flat base, thestationary contact carrier consists of a cup, which is countersunk in aplate and has slots for guiding the flat base, which slots have a windowto the outside at the bottom of the cup, the resilient noses of the flatbase snap into the window and are freely movable between the stops, acylindrical compression spring is provided, which bears on the bottom ofthe cup and on shoulders of the flat base, and at least two wire springsare provided, which are round or angular in cross section and cross theV-shaped wire spring at right angles and are guided in grooves againstyielding laterally, and in noses against lifting from the baseplate andyielding to one side, said wire spring terminating directly in clampingmeans.

In a development of the invention regarding the key head, one end of theflat base consists of crossing tabs, which are received in the cavity ofthe detachable key cap when the same is mounted, the flat base is guidedin grooves in the cavity of the key cap, and noses of the flat base snapinto recesses of the grooves in the cavity of the key cap and enable thekey cap to snap in and to be held in position.

In a further embodiment of the regarding the key head, each key isprovided with a digit or a symbol so that the wiring expenditure can beoptimized by a free selection of the sequence of keys.

In a particularly advantageous, further development of the invention,the symbols consist of different colored keys.

According to the invention, the limbs of the V-shaped springs include asmaller angle at the apex of the V than at the ends of the limbs and theangle is changed continuously or in a step, e.g., approximately in themiddle of the limbs.

In a further embodiment of the invention regarding the clamping devicefor holding the stationary contact members in position, the clampingdevice for directly holding the stationary contact spring wires at leastat one end consists of rectangular insulating walls, which are at rightangles to the base plate and are closed on three sides and serve forreceiving a square nut, said walls have a through aperture for receivingthe stationary contact wire springs, through apertures for theconnecting bolts and apertures for receiving the lugs of the cover plateand a bolt are provided, and the ends of the fixed contact spring wiresare bent, preferably curved, and are clamped by the screw between thecover plate and the nut and held in the base plate by the lugs.

Further according to the invention, the through aperture for theconnecting bolts and the apertures for receiving the lugs of the coverplate form a single aperture.

Further according to the invention, the assembling opera tion can befacilitated in that the clamping devices are arranged in rows one besidethe other and in steps on different levels. To facilitate the connectionof plug joints, it is a feature of the invention that the cover platehas a short lug, which is to be passed through a corresponding apertureand to be reversely bent or pivotally moved, and an extended lug, whichis to be passed through another aperture and for reverse by bent andpassed out through a window in the step, and a plug joint is adapted tobe connected to the extended lug.

In a preferred embodiment of the invention, the assembling of the flatbase in the grooves of the cup is facilitated in that the ends of thegrooves are beveled in the form of a roof.

Finally, the ribs provided in the flat base and serving to guide theV-shaped spring, may, in accordance with the invention, be extendedsubstantially in the longitudinal direction of the flat base and formreinforcing ribs.

An illustrative embodil'nent of the invention will now be explained morefully with reference to the FIG.

The limbs 53 and 54 of the V-shaped wire spring 3 serve to electricallyconnect the two conducting wires 20 and 21 when the key cap 2 isdepressed, where the cap 2 has been fitted on top of the flat base 1.The V-shaped wire spring 3 is snapped into the hole 4 with the apex ofthe spring directed toward the base plate 9. The spring 3 is guidedagainst lateral movement by the ribs 5 and ,6. The V-shaped wire spring3 can move between the ribs Sand 6 at right angles to the flat base 1and to the ribs. in position of rest, the V-shaped wire spring cannotcontact either of the conductors 20 and 21.

The base plate 9 contains the cup 10 having slots 11 and 12. The spring19 is first inserted into the cup 10, then the conductor 20 into thegroove 22 and the nose 25, and the conduc' tor 21 into the noses 24 and26 and the groove 23.

The conductor ends 55 and 56 are gripped by the clamping device 27, 28and the clamping device 38, respectively. The other ends are freelymovable.

Provided with the V-shaped spring 3 and the key cap 2, the flat base 1is now inserted into the space between the conducting wires 20 and 21with its noses 7 and 8 entering grooves 11 and 12. This operation isperformed against the pressure of the spring bearing on the shoulders 17and 18, and is facilitated by the rooflike bevels 57 and 58. The noses 7and 8 are bent inwardly toward the V-shaped wire spring and are thendepressed into the windows 13 and 14 and snap into the same.

The lower and upper edges 15 and 16 of the window 13 and thecorresponding edges of the window 14 cooperate with the noses 7 and 8 tocontrol the freedom of movement of the flat base 1. In a position ofrest, the stress of the cylindrical compression spring 19 holds the base1 in its upper position. When depressed, the base 1 is in its lowerposition against the stress of the cylindrical compression spring 19 butonly as long as pressure is applied to the key cap 2.

The flat base can easily be removed. It is sufficient to hold the basein a somewhat oblique position and to urge the resilient nose 7 or 8through the window so that the base can be pulled out upwardly. In thiscondition the cylindrical spring 19 contacts preferably the conductors20 and 21.

The invention is not restricted to the use of only one resilientcontacting device. A plurality of contacting devices can be arranged inthe same plane as the flat base 1. ln such a case, the conductors 20 and21 must be correspondingly bent laterally. The conductor 20 may be thecommon return con ductor from all these contacting devices to a sourceof current.

The clamping devices 27, 28 and 38 are an essential part of the deviceaccording to the invention. They are held in position due to the specialfonn of the ends 55 and 56 of the conducting wires 20 and 21.

Each clamping device for locating the stationary contact members of thecontacting device according to the invention consists of two rectangularinsulating walls such as 27 and 28. These walls are at right angles tothe base plate 9 and closed on three sides and serve to receive a squarenut 33. These walls have a through opening 29 for the fixed contactspring wire 20 and a hole 30 is provided for receiving a connecting bolt35. The square nut 33 is received in the rectangular space defined bythe sidewall. Above the nut, there is the U-shaped end 55 of theconducting wire 20 and above the same the cover plate 34, which has lugs36 and 37, which are inserted into the holes 31 and 32 and are held inposition on the under side of the base plate 9 by being laterally bentor bonded. The bolt 35 urges the cover plate 34 and the nut 33 againsteach As the end 55 is clamped, the conductor 20 is inserted under thenose 25, the conductor 20 is inserted in the groove 22, and theresilient conducting wire is held in position. During the movement ofthe V-shaped contact spring 3, the conductor 20 can yield resiliently tosome extent within the limits defined by the nose 25 and the groove 22.

ln a preferred embodiment of the invention, the clamping devices arearranged one beside the other. In a further preferred embodiment of theinvention, such rows are arranged in steps so that the connection toequipment and leads outside the equipment can be established easily andin a clear arrangement.

The drawing shows the clamping device 38, which is disposed on a levelbelow the clamping device 27, 28. The end of the conductor 21 iscorrespondingly offset and is guided, e.g., in a separate groove on theleft on the sidewall 27 (not shown). The sidewall 27 may be a part ofthis groove. The components of the clamping device 38 are the same asthose of the clamping device 27, 28.

In a further embodiment of the invention, one lug of the cover plate isextended, such as the lug 61 in the drawing. The lug 61 is insertedthrough the slot 63 and moved out at the forward edge of the parallel tothe base plate 9. A plug may be fitted on this extended lug to receive adetachable connection.

When the conducting wire 21 has been installed, it can also yieldresiliently to the outside when the keys are depressed. This yielding islimited by the groove 23 and the noses 24 and 26.

The grooves and 6 may be extended to form ribs 64 and 65 in order toimprove the stiffness of the flat base 1.

The key caps 2 are removable, Ribs 43, 44, 45, 46 inside the key capcooperate with recesses 48 and corresponding noses 47 to hold the keycaps in position. The ribs 39 and 40 serve for stiffening and for astraight guidance of the key cap on the flat base 1.

In the previously known contacting devices, such as in domestictelephone systems, stationary key heads, which were connected to thebases of the movable contact carriers, were always used and wereprovided with consecutive numbers. As a result, four such keys enabledthe provision of only four numbers. In such circuit the calling stationmust be included in those numbers. As there are only numbers 1 to 4 ineach station, different telephone directories had to be used for eachstation as each number was not associated with one and the same stationin each station.

An important advance toward unification has been ea established'by theprovision of detachable key caps and the supply of one additional number(e.g., the supply of key caps 1 to 5 with four keys). In a modificationof this invention, colored key elements rather than digits are used andonly one color is associated with each station.

The resilient electrical contacting device according to the inventionhas the advantage that there is a considerable saving in costs due tothe reduction in the number of conventional parts and in assemblingtime. The tolerances of the components may be very large so that anindustrial mass production at low cost is enabled.

The fact that the contact wires are resilient and the arrangement of thecrossing wires according to the invention results in a self-cleaning ofthe contacts. The provision of the crossing points avoids a soiling ofthe contacts.

It is generally sufficient to guide the flat base 1 in the grooves 11and 12. If a cap having apertures for the key head is disposed over thebase plate, these apertures will assist the guidance of the movablecontact carrier.

While the principles of the invention have been described above inconnection with specific apparatus and applications, it is to beunderstood that this description is made only by way of example and notas a limitation on the scope of the invention.

We claim:

1. A resilient electrical contacting device comprising a movable contactcarrier, a stationary fixed contact carrier, and two conductors, saidmovable contact carrier including a flat base of plastic material, saidflat base having mounted on one end a detachable key cap and on theother end a V-shaped wire spring, said V-shaped wire spring having a tipadapted to snap into an aperture of the flat base and limbs guided byribs of the flat base, the flat base including at the other end twonoses which protrude beyond the width of the flat base. the stationarycontact carrier including a cup which is countersunk in a flat plate andhas slots for guiding the flat base, said slots having windows towardthe outside at the bottom of the cup, the noses of the flat basesnapping into said slots and being movable between stops at the ends ofsaid slots, a cylindrical compression spring bearing on the bottom ofthe cup and on shoulders of the flat base, said two conductors includingtwo wire springs which cross the V-shaped wire spring at right anglesand are guided in grooves in the stationary contact carrier againstyielding laterally, and noses which guard the two wire springs againstlifting from the stationary contact carrier and yielding to one side,said two wire springs terminating directly in clamping devices.

2. A contacting device according to claim 1, in which one end of theflat base consists of crossing tabs, which are received in a cavity ofthe detachable key cap when the same is mounted, the detachable key capincluding ribs forming grooves for guiding the crossing tabs, and nosesforming part of the flat base snapping into recesses in the grooves inthe cavity of the detachable key cap to enable the detachable key cap tosnap in and to be held in position.

3. A contacting device according to claim 1, in which the limbs of theV-shaped wire spring are essentially parallel near the apex of the V anddiverge beyond bends near the middle of the limbs.

4. A contacting device according to claim 1, in which the clampingdevices for directly holding the two wire springs at one end includerectangular insulating walls at right angles to the stationary contactcarrier which are closed on three sides and serve to receive a squarenut, apertures in said walls to accept the two wire springs, aperturesfor receiving connecting bolts, and apertures for receiving lugs of acover plate, and the ends of the two wire springs are bent and areclamped by the connecting bolts between the cover plate and the nut andheld in the flat plate by the lugs.

5. A contacting device according to claim 4, including a cover platehaving a short lug which is to be passed through an aperture andreversely bent, and an extended lug which is to be passed throughanother aperture and reversely bent.

6. A contacting device according to claim 1, in which the assembling ofthe flat base in the grooves of the cup is facilitated in that the endsof the slots are provided with rooflike bevels.

7. A contacting device according to claim 1, in which the ribs in theflat base are extended substantially in the longitudinal direction ofthe flat base to guide the V-shapcd wire spring and to form reinforcingribs.

1. A resilient electrical contacting device comprising a movable contactcarrier, a stationary fixed contact carrier, and two conductors, saidmovable contact carrier including a flat base of plastic material, saidflat base having mounted on one end a detachable key cap and on theother end a V-shaped wire spring, said V-shaped wire spring having a tipadapted to snap into an aperture of the flat base and limbs guided byribs of the flat base, the flat base including at the other end twonoses which protrude beyond the width of the flat base, the stationarycontact carrier including a cup which is countersunk in a flat plate andhas slots for guiding the flat base, said slots having windows towardthe outside at the bottom of the cup, the noses of the flat basesnapping into said slots and being movable between stops at the ends ofsaid slots, a cylindrical compression spring bearing on the bottom ofthe cup and on shoulders of the flat base, said two conductors includingtwo wire springs which cross the V-shaped wire spring at right anglesand are guided in grooves in the stationary contact carrier againstyielding laterally, and noses which guard the two wire springs againstlifting from the stationary contact carrier and yielding to one side,said two wire springs terminating directly in clamping devices.
 2. Acontacting device according to claim 1, in which one end of the flatbase consists of crossing tabs, which are received in a cavity of thedetachable key cap when the same is mounted, the detachable key capincluding ribs forming grooves for guiding the crossing tabs, and nosesforming part of the flat base snapping into recesses in the grooves inthe cavity of the detachable key cap to enable the detachable key cap tosnap in and to be held in position.
 3. A contacting device according toclaim 1, in which the limbs of the V-shaped wire spring are essentiallyparallel near the apex of the V and diverge beyond bends near the middleof the limbs.
 4. A contacting device according to claim 1, in which theclamping devices for directly holding the two wire springs at one endinclude rectangular insulating walls at right angles to the stationarycontact carrier which are closed on three sides and serve to receive asquare nut, apertures in said walls To accept the two wire springs,apertures for receiving connecting bolts, and apertures for receivinglugs of a cover plate, and the ends of the two wire springs are bent andare clamped by the connecting bolts between the cover plate and the nutand held in the flat plate by the lugs.
 5. A contacting device accordingto claim 4, including a cover plate having a short lug which is to bepassed through an aperture and reversely bent, and an extended lug whichis to be passed through another aperture and reversely bent.
 6. Acontacting device according to claim 1, in which the assembling of theflat base in the grooves of the cup is facilitated in that the ends ofthe slots are provided with rooflike bevels.
 7. A contacting deviceaccording to claim 1, in which the ribs in the flat base are extendedsubstantially in the longitudinal direction of the flat base to guidethe V-shaped wire spring and to form reinforcing ribs.